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Monday, 19 February 2018

If on a winter's night a traveller ...

Out on a nocturnal expedition, and discovered I wasn’t the only one.

A shape on the path, its coloration blending in orangely with the surroundings under the sodium light, adumbrated by shadow. There as still as a statue, as if it had both just materialised that instant and also been there all along for centuries, was a large frog, squatting crouched in its sumo pose, jewel eye impassively taking in the scene, weighing up a next move.

Time and toad wait for no one ....

A few more steps and there was another, then another, and a mature palmate newt, then another newt, a toad, then more toads and frogs, at intervals along the church path. All 3 of our common species were on the march, on one short brief stretch of urban Exeter footpath. One could imagine the earth had belched them up from some netherworldly subterranean place, an amphibian version of a Stanley Spencer mass resurrection for spring.

The last few nights had been mild and wet, constantly damp, intermittent rain, then more rain, with nocturnal temperatures tipping above 5oC. This must have been the trigger to stir from hibernation, emerging from damp corners of gardens from under stones, paths, sheds, and the soil.

It’s easy to forget about the terrestrial part of the amphibian lifecycle, and that most of the amphibian year is spent away from the pond - apart from the breeding season. In these squally warmer wet nights, the moist atmosphere aids breathing through the skin and gives less risk of dehydration, plus means that ditches and ponds may be filling up. Collective emergence gives better odds that any one individual will survive the gathering attention of predators.
Toadzilla, on the march (on some screens this may be too dark to see)
It’s said that the older and larger individuals make the migration trek earlier, possibly trading off safety in return for the chance to claim first the best breeding opportunities. Certainly the participants in this evening’s ‘frogtide’ were mature animals, collisions leading to amplexus grabs and toads inflating in alarm, presaging the contests to come. Soon there will be spawn, soon spring will be on the way.

Sunday, 14 January 2018

A Hawfully Big Adventure

From October 2017 onwards we’ve been experiencing a massive ‘irruption’. Several thousands of usually rare Hawfinches arrived unexpectedly in the UK this winter, said to be due to a good breeding year, followed by failure of food crop sources in Germany and Romania, with journey possibly aided by storm Ophelia, and any return trip possibly postponed by storm Eleanor. Some have made it as far as central Exeter, loitering for a time around St Thomas churchyard and the pleasure grounds over the road, and then at Exwick Cemetery. 

Totally Hawsome: Exwick cemetery woodland burial area
This is a special bird and a special opportunity. The national breeding population hovers around 500-1000, with fidelity to certain locations, and stronghold in south east England1. These last few months have welcomed thousands to the UK, sometimes seen in flocks fifty or more strong, instead of the average grouping of 7-8. 

Size matters; this largest finch, with the biggest beak and head, the longest scientific name among our UK songbirds Coccothraustes coccothraustes, and in the largest numbers - surely something this distinctive should be easy to spot? 

Afraid not. Hawfinches are "notoriously self-effacing" and "the most challenging songbird to observe well"2. Generally a woodland specialist, secreted circumspectly high in the upper canopy, fawn plumage blending in with bare trunks, with a relatively quiet infrequent song, and flying off stealthily at the slightest hint of disturbance, the spotter’s traditional first - and last - view of a Hawfinch is a flash of white feathers on long dark tapering wings either side of a short tail, in a bounding flight…. as they disappear away out of sight over the treetops….

Chances of good sightings of these enigmatic visitors at Exwick cemetery then seemed low. But we could increase the odds maybe with some received knowledge and strategy: start with any woodland areas; scan the uppermost treetops; check especially cherry trees; look out for slight movements of silhouettes which turn out to be unusually large perching birds with short tails; be still, watchful, patient. There were not going to be many close-up photo opportunities. 

Exwick cemetery has lots of cherry trees as well as numerous grand old standard trees. A green burials woodland area, the treetops of which can be viewed from paths, seemed promising in theory. A flock of 5 Hawfinches was reported on Saturday afternoon, on cherry trees at the top of the site. 

In the first hour we tried a few different vantage points. Movements turned out to be long-tailed tits, chaffinches, a bullfinch, goldcrest, blackbirds and squirrels, once a sparrowhawk darting between the trunks. There was a keen northerly wind. Looking up at the canopy and thin glare of the low winter sun, some minutes were spent in careful intense observation of a clump of leaves.
There's a Hawfinch in this pic somewhere - can you spot it?

And then, the slightest shifting out from behind the top of a cherry trunk on to an upper bough, part of a bird shape which seemed to be playing a trick of perspective appearing larger by being closer. Except it was indeed large, deftly plucking a cherry with an enormous beak. Once glimpsed, and locked on to with the binoculars, it was unmistakable. 

The characteristic bill allows monopolisation of a specialised feeding niche, on tough-coated haws, sloes, cherries especially, and beech mast, amongst other seeds. It’s possible to tackle these when your face is equipped with a pair of bolt croppers. For the Hawfinch's scientific name Coccothraustes ‘kokko’ from Greek means ‘kernel’ and ‘thrauo’ ‘I break in pieces’.

This might be it .... or not

Nature's engineering design is much more sophisticated than bolt-croppers: 4 horny pads inside the upper and lower palates hold the seed or stone in place, while distributing bite force evenly across the massive cheek muscles – the reason for the heavy-set neck and head. The crunch of the bite force is estimated to be 1000 times the bird's own weight, exerting 50-60 g/sm (1950s experiments found that 27-43kg was needed to crack open cherry stones). It is said bird ringers' knuckles, when trying to ring Hawfinches, regularly also feel this force3

It was fascinating to observe the bill in action, not just the strength but also the nimbleness dealing with the cherry stones. Our vigilance was rewarded with sightings of 3-4 more birds. Satisfied with the morning's venture, we went in search of a warming cup of tea, and to see how the photos came out.... 

Postscript: as ever, I should leave it to the professionals. Here's a pic posted on the proper Devon Birds website - for more authoritative interweb information about Devon's birds and sightings, this is the place to visit.
from Devon Birds website - Hawfinch at Haldon by J. Deakins

Wikipedia and Birdtrack website 2017 
Peter Lack 1986 The Atlas of Wintering Birds in Britain and Ireland Poyser, London
3 from M Cocker and R Mabey 2005 Birds Britannica Chatto & Windus, London, and Jonathan Elphick 1997 / reprint 2001 The BBC Birdwatcher’s Handbook A Guide to the Birds of Britain and Ireland BBC Worldwide Ltd 
    – Jonathan is speaking to Topsham Birdwatching and Naturalist group on Friday 9 March